Impact extrusion is a process utilized to make metallic containers and other articles with unique shapes. The products are typically made from a softened metal slug comprised of steel, magnesium, copper, aluminum, tin or lead. The container is formed inside the confining die from a cold slug which is contacted by a punch. The force from the punch deforms the metal slug around the punch on the inside, and the die along the outside surface. After the initial shape is formed, the container or other apparatus is removed from the punch with a counter-punch ejector, and other necking and shaping tools are used to form the device to a preferred shape. Traditional impact extruded containers include aerosol containers and other pressure vessels which require high strength, and thus use thicker gage and heavier materials than traditional aluminum beverage containers. Because of the thickness and strength requirements of these containers, the cost to manufacture the containers may be significant when compared to conventional metal beverage containers which generally utilize 3104 aluminum. In a conventional impact extrusion process, almost pure or “virgin” aluminum is used due to its unique physical characteristics, and is commonly referred to as “1070” or “1050” aluminum which is comprised of at least about 99.5% of pure aluminum.
Due to the complexity of creating complex shapes with soft metals such as aluminum, critical metallurgical characteristics must be present for the impact extrusion process to work. This includes but is not limited to the use of very pure, soft aluminum alloys, which typically contain at least about 99% pure virgin aluminum. Because of this requirement, the use of recycled materials, for example aluminum alloys 3104, 3105, or 3004 scrap aluminum, have not been feasible for use in the impact extrusion process for aerosol and beverage containers.
Thus there is a significant need to find a lightweight yet strong aluminum alloy to form impact extruded containers and other useful articles, and to utilize scrap aluminum from other manufacturing processes to benefit the environment and save valuable natural resources.